Ai Weiwei's installation “With Wind” is presented at the Golden Gate National Recreation Area's Alcatraz Island near San Francisco, California, September 24, 2014. Starting September 27, the former island penitentiary turned U.S. national park in San Francisco Bay will offer visitors the opportunity to view seven installations custom-designed by the artist and activist Ai Weiwei. (Photo by Beck Diefenbach/Reuters)

A members of the media uses a mobile phone to take pictures of Ai Weiwei's installation “Blossom” in the hospital ward of Golden Gate National Recreation Area's Alcatraz Island near San Francisco, California, September 24, 2014. “Blossom” consists of toilets, sinks and baths filled with ceramic flowers. (Photo by Beck Diefenbach/Reuters)

“Iron Tree”, a sculpture by Chinese artist Ai Weiwei is seen displayed in a courtyard of the chapel at the Yorkshire Sculpture Park in Wakefield, northern England May 23, 2014. (Photo by Nigel Roddis/Reuters)

Chinese artist Ai Weiwei poses for a photograph with his installation entitled “Sunflower Seeds”, at its unveiling in the Turbine Hall at the Tate Modern gallery, in London October 11, 2010. (Photo by Stefan Wermuth/Reuters)

A gallery technician assembles a sculpture made from stainless steel bicycles entitled “Forever” by Ai Weiwei at the Lisson Gallery in London May 22, 2014. (Photo by Suzanne Plunkett/Reuters)

The installation “He Xie” by Chinese artist Ai Weiwei is pictured during a media preview of the exhibition “Evidence” at the Martin-Gropius Bau in Berlin, April 2, 2014. (Photo by Fabrizio Bensch/Reuters)

A visitor takes a photograph of the an installation by Ai Weiwei entitled “Sunflower Seeds”, at its unveiling in the Turbine Hall at the Tate Modern gallery in London October 11, 2010. (Photo by Stefan Wermuth/Reuters)

A general view of the installation “Stools” by Chinese artist Ai Weiwei pictured during a media preview of the “Evidence” exhibition at the Martin-Gropius Bau in Berlin, April 2, 2014. (Photo by Fabrizio Bensch/Reuters)

A woman walks next to the installation “IOU”, made up of certificates of debt, by Chinese artist Ai Weiwei during a media preview of the exhibition “Evidence” at the Martin-Gropius Bau in Berlin, April 2, 2014. (Photo by Fabrizio Bensch/Reuters)

A work titled “grapes” by artist Ai Weiwei of China is displayed during a media tour of the Perez Art Museum Miami (PAMM) in Miami, Florida December 3, 2013. (Photo by Joe Skipper/Reuters)

A man looks at the sculptures “Circle of Animals” by Chinese artist Ai Weiwei during a media preview of the exhibition “Evidence” at the Martin-Gropius Bau in Berlin, April 2, 2014. (Photo by Fabrizio Bensch/Reuters)

Visitors look at the installation called “Bang” by China's artist Ai Weiwei at the German pavilion during the 55th La Biennale of Venice May 29, 2013. (Photo by Stefano Rellandini/Reuters)

A view of an installation as part of the “S.A.C.R.E.D” exhibition by Chinese artist Ai Weiwei during the 55th La Biennale of Venice, in the church of Sant'Antonin in Venice May 28, 2013. (Photo by Stefano Rellandini/Reuters)

A view of an installation as part of the “S.A.C.R.E.D” exhibition by Chinese artist Ai Weiwei during the 55th La Biennale of Venice, in the church of Sant'Antonin in Venice May 28, 2013. (Photo by Stefano Rellandini/Reuters)

A view of an installation as part of the “S.A.C.R.E.D” exhibition by Chinese artist Ai Weiwei during the 55th La Biennale of Venice, in the church of Sant'Antonin in Venice May 28, 2013. (Photo by Stefano Rellandini/Reuters)

A view of an installation as part of the “S.A.C.R.E.D” exhibition by Chinese artist Ai Weiwei during the 55th La Biennale of Venice, in the church of Sant'Antonin in Venice May 28, 2013. (Photo by Stefano Rellandini/Reuters)

An artwork by Chinese artist Ai Weiwei, titled “The Dog Mobile: A car for Francis Bacon by Ai Weiwei”, with images of a dog painted on a Mercedes Benz G-class, is displayed at an exhibition hall in Hong Kong November 29, 2011. (Photo by Bobby Yip/Reuters)

A woman looks at an art installation named “Forever Bicycles” by dissident Chinese artist Ai Weiwei during a media preview of the “Ai Weiwei Absent” exhibition in Taipei October 28, 2011. (Photo by Pichi Chuang/Reuters)

A creation named “Watermelon” by Chinese artist Ai Weiwei is displayed during a media preview of the “Ai Weiwei Absent” exhibition in Taipei October 28, 2011. (Photo by Pichi Chuang/Reuters)

A visitor looks at Ai Weiwei's “Circle of Animals/Zodiac Heads” at Somerset House in London May 11, 2011. (Photo by Andrew Winning/Reuters)